Endoscopic Vein Harvest (EVH) has become the standard method for dissection and harvest of conduit used in coronary artery bypass surgery (CABG). Recent data show that, while overwhelmingly preferred by patients, EVH has been associated with a decrease in long-term graft patency rates. While yet to be definitively ascertained, this adverse outcome is thought to be associated with vessel trauma incurred during the endoscopic harvest procedure.
Currently, identification of blood vessels to be harvested endoscopically relies upon locating the vessel by white-light visual guidance. Following the course of the vessel during dissection and recognizing of side branches of this vessel by white light imaging is often problematic. Difficulties in recognizing the course of the vessel and/or identifying side branches may lead to trauma to the vessel, with the potential for sub optimal patient outcome.
Accordingly, there is a need to identify an appropriate vessel, to track the course of the vessel and to identify side branches; for example, this can be accomplished by observing a fluorescence image of the vessel of interest and allowing this image to be displayed in a manner that permits full appreciation of the anatomy.
The search for a more favorable imaging modality is continuing, with recent interest in the use of indocyanine green (ICG) fluorescence imaging, wherein blood circulation is assessed on the basis of a fluorescence signal. Fluorescence in ICG with an emission peak around 830 nm occurs as a result of excitation by radiation in the near-infrared spectral range. Excitation light with a wavelength around 800 nm can be produced, for example, by a diode laser, light emitting diode (LED), or other conventional illumination sources, such as arc lamps, halogen lamps in conjunction with a suitable bandpass filter.
ICG strongly binds to blood proteins and has previously been used for cardiac output measurement, hepatic function evaluation, and ophthalmic angiography, with few adverse reactions. ICG fluorescence imaging previously has been successfully used to assess and validate patency of arterial and venous anastomoses to identify insufficient ones that might lead to post-operative flap and graft failure.
However, there is still need to improve preoperative location and, optionally, the determination of the dimensions of blood vessels to be harvested in an endoscopic procedure by a simple, minimally-invasive method. This invention addresses these needs.